Tracheostomy cannula

ABSTRACT

The present invention relates to a tracheostomy cannula with a small balloon or cuff (2) positioned posteriorly (or cranially) to the tube (1) which is consequently shorter. This tube (1) has a collar (5) that encircles the tube on its proximal portion and prevents air leakage through the stoma. The &#34;cuff&#34; (2) also may communicate with the environmental air by means of conduits (6) that may be flexible. Since the component structures of a cannula so formed progress only a small distance caudally into the trachea, some complications, if not completely avoided, are better guarded against. Thus, there is when using the present invention less stimulus to a coughing reflex. Moreover, its cleaning and that of the trachea are simpler, and a tracheo-innominate fistula will rarely occur.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a tracheostomy cannula with the formatand distribution of its components designed so as to prevent theso-called tracheo-innominate fistula and the smallest stimulus to thecoupling reflex, and to allow the cannula to be easily cleaned.

2. Description of the Related Art

The immense majority of cannulas for tracheostomy follow a basic conceptthat, in itself, is the model most used today. The cannula consists of acurved tube which acts as a passage for air between the patient'strachea and the environment or an artificial respirator. Since it isoften necessary to use positive inspiratory pressure by means of theabove-mentioned respirators, this tube is enveloped at its caudal end bya small balloon inflatable with air or liquid, which, by adheringcompletely to the internal lining of the trachea by means of across-section of the trachea, prevents the air insufflated by therespirator from escaping into the environment and/or into the larynx andpharynx, so that air may be conducted to the caudal section of thetrachea, the bronchi and pulmonary alveoli. Yet another function of thissmall balloon or "cuff" is to support the tube itself inside thetrachea. The dimensions of the cannula vary a great deal, especiallywhen considering pediatric models. However, for adults the limits arequite close, and the distance from the cranial edge to its distal (orcaudal) extremity in an orthogonal projection parallel to the axis ofthe trachea is on the order of 4 to 5.5 cm. in usual models. Thisdistance is represented by distance "x" in FIG. 1 of the invention,which will be described later.

For a better understanding of the development of the present invention,it should be noted that many complications of a tracheostomy depend onirritations caused by the tube itself and/or by the small balloon. Thus,the longer the cannula tube, the greater the stimulus to coughing andthe harder it is to clean both the cannula and the trachea. However, thegreatest aggravating factor of such cannulas are the lesions to thetrachea walls and/or to structures contiguous to the trachea which areproduced by the possible compression exerted on these tissues by thetube, mainly in its caudal extremity and/or by the small balloon,especially if the pressure in the trachea's interior is very high. Suchlesions range from a simple ischaemia to real perforations, withresulting secondary complications that are essentially obstructive,infectious and/or hemorrhagic. Among the latter can be noted theso-called tracheo-innominate fistual - an abnormal passage between thetrachea and the innominate artery through such perforations. Thisfearful intercurrent process may cause severe hemorrhages which, whenthey do occur, lead to a case fatality rate of over 92%. Its occurrenceis intimately related to the dimensions of the cannula: the longer itis, the greater the risk to the patient. This risk is already uncommonlyhigh since the distance from the upper limit of the secondcartilagineous trachial ring-cranial limit of the great majority oftracheostomies, up to the upper crossing point of the trachea with theinnominate artery is, on the average for adults, about 3.3 cm, whereasthe same distance measured on the cannula to its caudal extremity isapproximately between 4 and 5.5 cm, as mentioned above.

Another "inconvenience", not properly a complication, in the use ofthese tracheostomy cannulas of the prior art is the need for a tape tobe fitted around the neck of the patient and tied to the proximalextremity of the cannula in order to hold and fix it in place. However,there is a known model on the North American market which, among othersmall improvements, does away with the use of tapes around the neck andlends itself to the prevention of this tracheo-innominate fistula. Itconsists of a simple tube placed between the skin of the neck and theanterior wall of the trachea, and it is fixed there by its proximal anddistal edges. Since it does not progress caudally along the interior ofthe trachea, if it does not do away with, it greatly reduces the risk ofthe onset of this complication. This cannula only hides the trachealstoma without, however, allowing the use of positive inspiratorypressure through artificial respirators, which renders its useimpossible in various patients to be tracheostomized. Besides, it isdifficult to remove them from the tracheal stoma and these may, althoughon a smaller scale, lead to infectious, obstructive or hemorrhagiccomplications.

In short, whatever the model to be considered, there is still the riskof irritation on the part of the components of the cannula of the priorart, and the consequences tend to be more severe the more caudally thesecomponents progress through the interior of the trachea.

SUMMARY OF THE INVENTION

With the objective of generally decreasing the irritative potential oftracheostomy cannulas, but particularly concerning the lesser stimulusto the coughing reflex, ease in cleaning both the cannula and thetrachea, and preventing a tracheo-innominate fistula, the cannula of thepresent invention was developed to include a small balloon or "cuff"positioned in the region posterior to the curved tube, which, by thispositioning, allows a reduction in its length.

BRIEF DESCRIPTION OF THE DRAWING

The tracheostomy cannula of the present invention may be betterunderstood by the description of the diagrams enclosed, which represent:

FIG. 1--Side view in elevation of the tracheostomy cannula of thepresent invention.

FIG. 2--View in perspective of this same cannula of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As can be seen from FIGS. 1 and 2, the tracheostomy cannula of thepresent invention consists of a curved tube (1) with a circular contourin cross-section, but which is quite short, with the distance "x" beingequal to about 1 cm which, besides decreasing the coughing reflex andfacilitating the cleaning both of the cannula and of the trachea,drastically reduces or possibly eliminates the risk of occurrence of atracheo-innominate fistula since the caudal extremity of the tubegenerally will not reach the region of the crossing of the trachea withthe innominate artery, also known as the brachiocephalic trunk. Itsextremity, known as proximal (3), or, in order words, that portion whichis exposed to the environment on introduction of the cannula into thetrachea, is equally circular in contour to the cross-section of the tube(1), but is has a radius that is slightly larger than that of the tubeand adaptable to artificial tracheas. The distal or caudal extremity(4), which is inside the trachea, also has a circular contouraccompanying the tube; however, its radius is slightly smaller than theradius of the tube, which renders its edge flatter and thereby lessensirritation to the trachea wall since, as is known, it is this edge ofthe distal extremity that is primarily responsible for lesions.

The small balloon or "cuff" (2) is placed posteriorly to the tube, withthe anterior or caudal portion closely adhering to it. Such positioningof the "cuff" should do away with the risk of the onset of atracheo-innominate fistula which is generally a result of a possibleirritation to the wall of the trachea, for the "cuff" will be far fromthe crossing of the trachea with the innominate artery. This "cuff" (2)also has an anterior extension which involves all of the proximal thirdof the tube (1) to form a "collar" (5) which, together with theconfiguration of the proximal extremity of the tube (1), will help tofix the cannula to the site, thereby dispensing with the uncomfortableuse of tapes around the neck and preventing the possible escape of airinsufflated under positive pressure into the environment. Since the"cuff" (2) can progress as far as the larynx on a level with the vocalcords, it will have great restraining capacity. Moreover, because itwill not have a tube crossing it, as in the unusual models, with theresultant low pressure in its interior, the cannula of the presentinvention considerably reduces the capacity for irritation to theendotracheal lining. In addition, the contour of this "cuff" (2) incross-section to the craniocaudal axis should be similar to theendotracheal lining of the majority of persons on this same plane, or,in other words, is elliptical, with a greater latero-lateral axis.

Control of pressure, and also the insufflation and deflation of the"cuff" (2), takes place by means of conduits (6) which may be flexible,and which connect the interior of the "cuff" (2) with the environment.The conduits (6) are fitted with caps, which may have a valve, as in thecase of other models of the prior art.

The material making up the cannula components should be as inert aspossible - that is, they should promote the least possible reaction, ornone at all, between the body and the instrument. For instance,polytetrafluorethylene, polyvinyl and many others may be used.

The tracheostomy cannula of the invention may, starting from the basicconcept described above, undergo some changes such as in its dimensions,which vary according to the patient's anatomical characteristics. Forexample, the curved tube may have two "central cavities", or in otherwords, an internal removable lining for cases of acute obstruction orfor facilitating cleaning. Also, the caudal extremity (4) may bedesigned so as not to be flat, should such a feature increase theresistance to the air flow in very small cannulas. However, this fact isalmost impossible to occur. In addition, the proximal extremity may beremovable, and in such a case, it will be coupled to the tube, forinstance, by means of threading which may lead it to the skin of thepatient's neck, should this contribute to fixing the cannula in place.The tube also may have contours other than a circular cross-section, andthe anterior extension or "collar" (5) may be of varied configurations,ranging from one analogous to that presented in FIGS. 1 and 2 to that inwhich it lines all of the intratracheal portion of the tube as far asits distal extremities, which may contribute to increasing therestraining capacity of the " cuff" (2) with a resulting low pressure inits interior and/or for better holding of the cannula. This same"collar" (5) also may be totally or partly adherent to the tube. Itsmobility, should it not be adhered, should facilitate sealing of thetracheal stoma, particularly when the dimensions of the trachea,principally the anteroposterior diameter, are extremely variable. The"collar" (5) also may communicate with the main compartment of the"cuff" (2), just as it may be of inflatable material. Pressure withinthe "cuff" (2) may be controlled by valves, as is already the case inother models, and the "cuff" (2) may be fitted with two separatecompartments so that one compartment may be insufflated while the secondis not, and vice-versa. This may occur alternately, which may decreaseirritation to the tracheal wall without loss of function, as occurs inthe case of periodic deflation of common "cuffs". The "cuff" (2) may(preferably) have all of its anterior portion adhering to the tube so asto always retain some adhesion. Also, the contour of the "cuff" mayassume forms other than elliptical, according to the anatomicalcharacteristics of the patient. In some rare cases it should be notedthat it may be necessary to wear tapes around the neck, which areattached to the proximal portion of the cannula. Finally, the materialmaking up the cannula may be of any kind, with preference being given,however, and logically so, to the more "inert" types.

The functions of the tracheostomy cannula of this invention are thus thesame as the "traditional" one. Its insertion into the patient iseffected by means of the classic tracheostomy techniques, and it isintroduced into the trachea with the "cuff" totally deflated. Then, onceit is in place, it is insufflated. As in existing models, insufflationand deflation, and also the control of pressure inside the "cuff", isdone by means of small sealable conduits that connect the interior ofthe small balloon to the environment.

I claim:
 1. A tracheostomy device for introduction into the trachea of apatient to form an artificial airway through the patient's throat,comprising:a hollow tube having proximal and distal end portions and abend intermediate of said end portions so as to form first and secondportions of said tube respectively including said proximal and distalend portions of said tube, said proximal end portion having a radiusslightly larger than that of said first portion of said tube and saiddistal end portion being arranged for insertion through a tracheal stomaand into a tracheal lumen of the patient's throat such that said secondportion of said tube extends in a first direction within the tracheallumen when said first portion extends through the tracheal stoma; aninflatable cuff; means for adhering said inflatable cuff to said tubeand for directing said cuff when inflated such that said cuff extendswithin the tracheal lumen of the patient's throat only in a seconddirection substantially opposite to said first direction; and means forinflating and deflating said cuff.
 2. A tracheostomy device as in claim1, wherein said cuff comprises a small balloon.
 3. A tracheostomy deviceas in claim 1, wherein said inflating and deflating means comprises atleast one flexible conduit.
 4. A tracheostomy device as in claim 1,wherein said adhering and directing means comprises a collar which ismovable along said tube.
 5. A tracheostomy device as in claim 1, whereinsaid adhering and directing means comprises a collar which isinflatable.
 6. A tracheostomy device as in claim 5, wherein said collarcommunicates with said cuff.
 7. A tracheostomy device as in claim 1,wherein said cuff is of such a size when expanded so as to expand withinthe limits of the tracheal lumen as far as the patient's larynx in orderto restrain said tube within the patient's trachea when saidtracheostomy device is inserted into the trachea of the patient.
 8. Atracheostomy device as in claim 7, wherein said adhering and directingmeans comprises a collar which is disposed on said first portion of saidtube so as to prevent air leakage through the tracheal stoma when saidtracheostomy device is inserted into the trachea of the patient.